Best A/B Y Box?

What I really want to do is the reverse of this, and have my bass and Moog synth go into the same input of my pedal board. I've tried products from JHS. Palmer, Whirlwind, Divided by 13, and they all weaken the bass guitar signal. Drastically, like 10db. The keyboard level isnt weakened. Thoughts? Thanks!

If you use a passive aby, the stronger signal will load down the weaker if you engage both inputs simultaneously. So the active keyboard is likely killing the output of your passive bass. You need an active preamp type selector or mixer to pull this off. If you are using an active aby that is intended to send to 2 outputs, that's not going to work right backwards.

As a bassist/synthesis, may I suggest a small mixer instead. Something like the Mackie 402VLZ4 would be perfect, as it has a switch for line/instrument level, and can handle stereo if needed. Lehle also makes great AB/Y boxes, but the mixer would allow for volume control per channel.

Hey dudes, I tried an active AB box and still wasn't stoked on the tone vs the purity of bass straight into amp. I'm now sending Synth to its own channel. This wasn't an option previously. Problem solved. Might have a never used Bassbone for sale... Bought one online, arrived after problem was solved. Might keep it for fun.